Understand UNDERMINING

One of the most common questions students ask in the suturing course that I teach is, “When do I undermine?”.

To help you better grasp this confusing topic... 🎥 Check out this quick video I created to learn more about UNDERMINING!

Generally, undermining is necessary for better aesthetic outcomes on tensioned wounds.

However, we have to be mindful of certain situations where undermining may not be a priority and, otherwise, not necessary.

In this quick read, I created this simple guide to help you better understand when to undermine.  It involves asking yourself - “WHO? WHAT? WHEN? WHERE? WHY?”. 

Let’s break it down further...

“WHO?” - Who are you undermining?

Understand who is your patient.  

Each patient is like a snowflake as far as their medical history, expectations, concerns on how they are going to scar, their age, and the list goes on.  This holistic approach will help you determine how you will surgically approach your patient. 

For example, are you taking care of an elderly patient with thin, loose skin and does not readily have concerns about the cosmetic appearance of her wound? Then, in this case, it is not necessary to undermine.  

On the other hand, is your other patient much younger, the surgery site is on robust skin, and he has heightened concerns about scarring? Then, in this case, you definitely do want to undermine, especially, if there is tension present.  

In these two case examples, thinking about who your patient is will help guide you to use your best medical judgement to determine if this is the right patient that will benefit from undermining.

“WHAT?” - What are you closing?

Understand what anatomic location you are performing surgery on.   

Is this a small cyst you are excising and located on the delicate face? Or is this a large Mohs defect located on a non-cosmetic area like an extremity or trunk?

In either area, If the skin has enough laxity to where you can place your subcuticular sutures meticulously, obtain great wound edge eversion and approximation, then undermining is most likely not necessary.  

However, If you are not successfully able to place your subcuticulars correctly because of the tension, eversion is difficult to achieve, then your approach will be different.  Undermine to help detach those underlying fibers to appropriately recruit skin for ease in closure.

“WHEN?” - When to NOT undermine? 

Think about times when you DO NOT want to undermine. 

Here are some specific examples of patients I have taken care of and undermining was NOT necessary. In all cases, the wound had mild to moderate tension.  The patient was… 

  • Incoherent, living in a nursing home 
  • On blood thinners and at higher risk for increased bleeding
  • Had dementia and family reported a history of him “picking” at his wound
  • An organ transplant patient with a higher risk of developing infections
  • A younger patient who was not concerned about scarring. The patient's priority was to quickly return back to work in a few days to take care of his family

In all these case scenarios, a discussion took place with the patient (and family when appropriate) to establish that the goal was for the patient to heal optimally and quickly.  Aesthetics and scarring was not a concern for either patient mentioned above. 

Being mindful of this, undermining would have been excessive and unnecessarily more time-consuming as it requires more hemostatic measures.  The risk outweighs the benefit in these situations. 

“WHERE?” - Where are you undermining? 

This overlaps with the what are you undermining because they both emphasize anatomic location. However, this question can serve as a reminder of DANGER ZONES to avoid.  

For example, many Mohs patients present with skin cancers on the temporal area.  This is, especially, an area to be cautious of because the risk of temporal nerve injury and paralysis is high.  In this case, I would be reluctant to undermine and avoid if possible.  The risk is not worth it. 

Are you working over delicate underlying structures - like removing a skin cancer over tendons in the hand?  In this case, avoid undermining as risk of injury, again, outweighs the benefit.

“WHY?” - Why are you undermining? 

These are 3 main reasons why to undermine:

  1. Alleviate tension on the wound
  2. It allows you to place your deep sutures when and where appropriate
  3. And helps evert the wound edges to minimize scarring when and where appropriate

SUMMARY

In summary, if you understand the - “WHO, WHAT, WHEN, WHERE, AND WHY” - of undermining, this will help you become a more confident dermatology provider as you perform procedures on your patient. 

Always know your comfort zone as a dermatology NP/PA and, simply, use your best medical judgment.

If you are not comfortable, defer care if necessary.

For reiteration, here is a summary of advantages, disadvantages, and technique pearls to remember when it comes it undermining: 

Advantages to Undermine

  • Permits closure of large or tight defects under tension that do not close easily
  • Reduces tension across tense defects by recruiting adjacent skin for closure
  • Frees up underlying attachments that could lead to lateral and downward pull, creating “inversion” (an inverted less aesthetically pleasing and more noticeable scar)

Disadvantages to Undermine

  • Potential impact on blood supply 
  • Increases likelihood of hematoma or seroma (by creating a deadspace)
  • More time-consuming as it requires more hemostatic measures
  • Risk of nerve damage

Pearls

  • Superficial undermining may increase the risk of damage to perforating vessels supplying the dermal plexus, increasing risk of necrosis  
  • Undermine deeper may reapproximation of deeper, well-vascularized structures rather than the thin dermis and epidermis
  • Undermining may be best performed with sharp dissection (with a scalpel) due to less tissue trauma as it avoids shearing forces that may be seen with blunt-tipped surgical scissors 

Leverage Your Skills

As dermatology NPs/PAs, I hope this article helped you better understand surgical pearls to be mindful of when performing surgery.  Also, techniques to use to achieve the best aesthetic results for your patient.

If you found this article helpful and want to dive deeper into building your confidence in your surgical skills, I created an advanced suturing course tailored specifically for dermatology NPs/PAs that will break down how to perform these suture techniques, step-by-step.  

The course will help you minimize scarring and improve your patients’ outcomes. If this sounds like a course that will help leverage your skills, click HERE to learn more!

Until next time...

Serving with GRATITUDE,

 

Theresa Talens DNP, FNP-C (TheresaSurgDermNP)

P.U.L.S.E. Dermatology & Procedures, Inc.

Where we believe in Precision. Ultimate Care. Leverage. Skills. Excellence.